AIC's 46th Annual Meeting

Excavating at an archeological site or probing a building can provide opportunities for architectural conservators and archeologists to work together. We do not collaborate as often as we should. This paper examines several projects where either there was collaboration or it was lacking and demonstrates how these two types of conservators examining materials together extracts a better understanding of what has been found. Building archeology is the study of a building. Despite the word archeology, it is not uncommon for Architectural Conservators to forget the archeologist. Removing floorboards for repairs in the Lower East Side Tenement Museum in New York City uncovered layers of objects including buttons, bones and tickets hidden in rats’ nests as well as material that had fallen between the floorboards over the course of a hundred and thirty years. Archeologists were a key part of the team retrieving and documenting this material for interpretation. Another type of project that would benefit from more collaboration is cemetery conservation. Often cemetery conservation is limited to repairing, aligning, and resetting markers, ensuring the cemetery looks tidy. But not all cemeteries had neatly placed gravestones surrounded by careful plantings. African American burials were often marked by grave goods or “offerings” placed upon graves. These items could be pottery and shells, as well as everyday objects such as cups, spoons, dolls heads, and clothing. Sandy Ground, a cemetery on the southern tip of Staten Island, was originally the resting place for an early free African American fishing community. It was vandalized in the 1990s. In an effort to restore the cemetery, it was cleaned up and many grave goods that were thought to be trash were lost. Archeologists can also forget that architectural conservators have extensive knowledge of historic building materials. During work on New York City Hall, a brick foundation was uncovered that was thought to be an early eighteenth century foundation. An examination by the architectural conservators found the walls were constructed of pressed brick and the mortar was natural cement, which dated the foundations well into the nineteenth century. On projects where archeologists and architectural conservators have worked together, a greater understanding of the building or site can emerge. An examination of the foundations of Federal Hall in New York City by a team consisting of an architectural conservator and an archeologist quickly dispelled the notion that the foundations were from a seventeenth century structure. An examination of walls discovered in Battery Park during work on the New York City subway system also benefited from a team of archeologists and architectural conservators working together. The excavated walls could not be saved, but the team was able to thoroughly document the techniques and materials used to construct them.

This talk describes the preservation of ancient graffiti in a rock-cut temple at the site of El Kurru in Sudan. El Kurru is the location of a royal burial ground of ancient Kush (a region located in modern-day northern Sudan), and the site encompasses multiple pyramid burials as well as two rock-cut funerary temples. The sandstone temple that is the focus of this project was built during the late Napatan period (ca. 350 BC), and its walls and columns are heavily inscribed with devotional graffiti from the Meroitic period (ca. 100 BC – AD 100). It is an impressive and unique structure, a source of pride for local residents, and an interesting and accessible feature for visitors. The ancient graffiti it contains provide a unique glimpse into the lives of individuals in antiquity, providing information about their thoughts, values, and daily lives. El Kurru’s sandstone monuments suffer from granular disintegration and other serious condition problems. Although the conservation of archaeological heritage is often complicated, it is especially challenging in Sudan due to a fragile national economy and comprehensive intertnational sanctions against the country (except - these were just lifted in October 2017! - so it might get better!). For these reasons, a holistic approach has been used to preserve the graffiti. Work began with a criterion-anchored rating (CAR) condition survey designed to identify, prioritize, and monitor condition issues. Chemical analysis of the stone was conducted, and treatment options including alkoxysilane consolidation and grout injection were explored. Preventive conservation strategies for the temple, including a protective shelter and increased community education, have also been developed. Finally, reflectance transformation imaging (RTI) was used to document the graffiti’s condition and create a virtual, visual catalog. This talk emphasizes key principles for guiding conservation at archaeological sites: practicality, flexibility, sustainability, and placing a high value on the contributions and wishes of stakeholders.

Algeria, the biggest country in North Africa with an area over 2 million square kilometers, has seven stunning UNESCO World Heritage sites. Among them are the earliest prehistorical sites in North Africa: the Oldwayen site of Ain el-Hanech, 1.8 million years BC. The area is enormous and it is difficult to administer effective long-term site management, preservation, and preventative measures. Not only are these cultural heritage sites threatened by extreme weather and climate, but human intervention, looting, vandalism, and terrorism. In order to protect these vast heritage sites, in the mid 2000s the Algerian authorities created the “Algerian Cultural Parks Projects” in partnership with the United Nations Development Program (UNDP) and executed by the Algerian Ministry of Culture. This launched a preventative conservation project applying a new model of local partnerships with Tuoareg and other tribal elders and stakeholders. 
Contained in this centralized Cultural Parks System are five major sites. Park of l’Ahaggar – over 633,000 km2; Tassili N’Ajjer Park – over 138,000 km2; Tindouf – over 168,000 km2; Atlas Saharian Park – over 63,000 km2; and Touat Gourarar Tidikelt Park – over 38,000 km2. The most important cultural heritage in this desert designation is the rock art. There are literally thousands of paintings and engravings out in the open, as well as sheltered in caves. They include masterpieces from the earliest period of art in the Sahara, the Large Wild Fauna Period. These life-size engravings of elephant, rhino, hippo, giraffe, and buffalo show a time when the Sahara was green and fertile. 
Conservation management in the Park of Ahaggar focused on the sites closest to roads and human communities, and then radiated out to the remote regions, often several days’ camel or jeep ride away. Preservation work commenced with detailed inventories including images, GPS, and narrative descriptions. For all the conservation surveys and routine checks, the Park recruited guides among the local population, namely the Touaregs. This detailed inventory work in remote regions was only possible with the collaboration and expertise of these partners, who are very familiar with the sites, locations, and routes. Most importantly, the communities and nomadic groups trust the guides; they often speak the same dialects, thereby facilitating a level of trust, access, and reliable information. The exchange of knowledge was two-way; the local Tuoareg elders and guides’ knowledge of the terrain, history, and symbolism of the sites was a rich resource that was documented as well. As archeological conservators, we were able to provide monitoring guidelines, compile massive data inventories, prioritize conservation site needs, and introduce an acceptable level of outside management to these sites. The relationships continue, as the guides serve on the “frontline” identifying areas of need and alerting archeological managers. This partnership has allowed for a much higher success in the protection of remote sites and movable cultural heritage, by developing a model based on trust, which has enabled government and university experts to work closely with local stewards. 

Grey bricks were produced manually and used as the major traditional building materials in ancient China. However, the characteristics of grey bricks make them vulnerable to water, salt and other environmental factors. Organosilicon materials, such as ethyl silicate, organosiloxanes, and silicone resin, have been tested as the effective protective materials for silicate based stones. In this study, we evaluated the effectiveness of different organosilicon materials on grey bricks by total and half immersions. The penetration depths, appearance alterations, water adsorptions, hydrophobic properties and compressive strengths were measured after the treatments. The samples were also experienced the salt solution immersion, freeze-thaw and UV aging tests to evaluate the durability of different conservation treatments. It is found that different characteristics of the organosilicon materials lead to different conservation performances, such as water repellence, consolidation effect and durability. But it remains difficult to determine an appropriate material for the conservation of ancient architecture built with grey bricks.

The MOCHE, Inc. Conservation Field School in summer 2017 (Huanchaco, Peru) provided training in preventive conservation and collections care on archaeological sites to binational undergraduate, graduate, and pre-program students . This paper reports on the program, which, co-directed by an archaeologist and conservator, aimed to bridge the gaps between training for work in the field and for work in museum collections. The program provided the opportunity for students to gain an encompassing perspective of the life-history of material culture from excavation through processing and analysis, to storage and display. We believe this holistic perspective is essential for all cultural heritage professionals, yet training programs of this type are not always available. Participants came to the program with varying levels of skills and experience in archaeology and conservation. American students and Peruvian students from the Universidad Nacional de Trujillo worked together on excavated materials from the regional survey led by UNT's archaeology lab. The students participated in archaeological excavation, finds processing, and recording, working hands-on with finds from the current and previous field seasons. As part of program curriculum they also learned about and engaged in basic conservation and collections management principles and practices. This work complemented the field school’s instruction in the materials that make up the archaeological record and the prehistory of the north coast of Peru. Students used close observation of the project collections to understand how the objects were made and used, and identified modifications in the objects from initial use-life and those occurring during deposition and post-excavation. Students visited archaeological storage facilities in Peru and learned about principles of safe storage and packing for archaeological finds. At the close of the program, students carried out some of the proposed improvements for safe objects packing using appropriate materials and methods. The students also visited archaeological sites and museums throughout the region to understand the benefits and risks that tourism development brings to local communities. This program is part of MOCHE Inc’s broader heritage preservation efforts. MOCHE, INC (Mobilizing Opportunities for Community Heritage Empowerment, http://savethemoche.org/) is an organization founded by archaeologists dedicated to improving the standard of living in impoverished communities, preserving archaeological sites, and promoting research and education on the rich cultural heritage of Peru. MOCHE Inc.’s work over the past 20 years in Peru has demonstrated that close community ties and community-oriented projects go hand in hand with preserving archaeological sites. This project demonstrates that preventive conservation need not be narrowly construed as concerning only tasks such as managing museum and storage environments (of course very important topics on their own) but can also encompass a variety of other community engagement and education activities crucial to the goal of heritage preservation.

Keeping it Vertical: Use of GIS to create a streamlined survey and work order system for a historic landscape Brooklyn’s Green-Wood Cemetery is home to over 200,000 historic monuments and over 7,000 trees throughout its 478 acres. As Green-Wood’s landscape ages and evolves, the need for more technologically advanced collections management software became apparent, a need which resulted in the creation of a unique ArcGIS-based collection management system. In Collector for ArcGIS, management and field crews input survey information such as date, material, dimensions, and conditions of a historic monument or caliper, condition, and taxonomic information of a tree. Managers also create work orders in Collector, which thanks to a first-of-its-kind script which links the two, automates the creation of a work-order in WorkForce for ArcGIS. Work orders are assigned by the Manager, and analytics related to executed work orders and efficiency metrics are reviewed in an Operations Dashboard. The link between Collector and WorkForce allows staff members to geotag work orders to specific trees and monuments while tracking their progress and saving survey information along the way. By utilizing the power of GIS, our software analyzes our landscape’s varied assets simultaneously and streamlines the implementation of the work necessary to maintain those assets, thus offering an enhanced, multi-faceted portrait of Green-Wood. Software such as this could be used across other large historic cemeteries, large archeological sites, city and state park land, throughout museum environments, and scores of other cultural landscapes. This presentation will guide viewers through the inception of the software and its application in the field. Founded in 1838 and now a National Historic Landmark, Green-Wood was one of the first rural cemeteries in America. By the early 1860s, it had earned an international reputation for its magnificent beauty and became the prestigious place to be buried, attracting 500,000 visitors a year, second only to Niagara Falls as the nation’s greatest tourist attraction. Crowds flocked there to enjoy family outings, carriage rides, and sculpture viewing in the finest of first generation American landscapes. Green-Wood’s popularity helped inspire the creation of public parks, including New York City’s Central and Prospect Parks. Green-Wood is 478 spectacular acres of hills, valleys, glacial ponds and paths, throughout which exists one of the largest outdoor collections of 19th- and 20th-century statuary and mausoleums. Four seasons of beauty from century-and-a-half-old trees offer a peaceful oasis to visitors, as well as its 570,000 permanent residents, including Leonard Bernstein, Boss Tweed, Charles Ebbets, Jean-Michel Basquiat, Louis Comfort Tiffany, Horace Greeley, Civil War generals, baseball legends, politicians, artists, entertainers and inventors.

Up to the middle of the nineteenth century, the “liquid-to-solid” organic materials that serve as architectural paints, coatings and adhesives represented the chemistry of natural products. The sources of raw materials were varied, including drying oils, tree resins, and animal and fish glues, but commercial users wanted products with greater ease of use, and better (and more consistent) performance. The earliest of these improved materials involved relatively simple modification of natural products, with industrial-scale experimentation giving us vulcanized rubber and cellulose nitrate. Improvements in the production of coal and oil distillates, and in the structural study of organic molecules, led to the first generation of phenolic resins and butadiene rubber in the early twentieth century. By 1930, many familiar materials—such as alkyd resins, PVC and Nylon 66—were starting to enter the marketplace. They set the stage for a broader revolution in polymer science that dramatically changed the work of architects, engineers and builders in the decades that followed.

For centuries, lead based paints have been the primary paints used on external woodwork on historic houses. However, recent changes in legislation related to VOCs (volatile organic components) and the restriction of the use of lead paint due to toxicity has meant that paint formulations have changed to meet the changing legislation requirements. In addition, there has been a growing interest in the use of "environmentally friendly" paints. For historic houses, the cyclical maintenance requirements of repainting external woodwork is a major financial consideration and as result, the need to assess the performance of the wide variety of paints available encouraged the National Trust to undertake a series of paint trials to assess sustainability as well as consideration of the visual appearance of the paint (a factor which is important in maintaining the historic appearance of our properties). In 2006, the National Trust began a series of external paint trials on 13 garage doors on one of our properties to assess the performance of the selected paints. The trials provided information about the sustainability of the paints based on visual evidence of cracking, flaking, color change and moisture penetration. Whilst informative, it was realized that the results could not provide a recognized methodology for comparing the paints' performance. As a result, a group of heritage organizations led by the National Trust decided in 2011 to conduct a series of trials at the Paint Research Association in order to provide an industry recognized standard testing procedure to assess 34 paints which were selected on the basis of those used by the members of the group as well those which were commercially available to ensure that they would still be available after the conclusion of the trials. In addition, a number of "environmentally friendly" paints were included to assess their performance. The trials began in 2012 and after four years of testing, the results enabled the group to evaluate the performance of the paints and select 10 paints which performed above average as well as a linseed based paint, a lead based paint and a ICP (internal comparison product used as a standard) to be used to coat a number of the original panels to assess their performance. It was felt that this test would reflect more accurately the method of repainting used on historic properties where the underlying paint layer is simply sanded to remove defects and then coated with a new paint layer. It would also provide information about the sustainability of applying a different paint system over an existing paint layer. This paper explains the procedures involved and the results to date which should provide guidance for historic properties to ensure that the most sustainable paint systems are applied to external wood work.

In May of 2016, members of the Department of Conservation and Technical Research at the Walters Art Museum began to investigate the original plaster walls in the library of 1 West Mount Vernon Place, which is now a part of the museum complex. This impressive family home was designed by architects Niernsee and Neilson and was completed by1851. After a series of other owners and uses, the building was given to the museum by the City of Baltimore in 1984. It subsequently underwent significant renovations and opened to the public in 1991 as a gallery of Asian Art. In 2016, after 25 years of use, upgrades to the HVAC system and the installation of a fire suppression system led to the temporary closure of the building and allowed for gallery refurbishments. When the conservation department was asked to remove fabric paneling from the library so that it could be replaced, they were surprised to find that the original painted ornamental plaster that had not been viewed since 1991 was largely intact. This raised and decoratively painted ornamental plaster was first covered with fabric in the 1890s when the house underwent significant alterations. At that time, many of the high points of the plaster had been chiseled off to allow the fabric panels to span the walls without distortion. In addition, later upgrades, including the installation of gas and electric lines for wall sconces and an air duct were made without regard to the plaster walls. Despite these interventions, the original color scheme and decorative painting were intact, especially in the protected upper areas of the walls. One interesting feature of the design was the use of faux wood graining on the raised plaster elements. The faux wood graining integrated the painted plaster with the surrounding woodwork. Early hand-colored photographs of the room also show that there was an elaborate ornamental plaster ceiling that was later covered with a wooden beam ceiling. Despite numerous alterations to the room, the conservation staff advocated for the preservation and display of this rare survival of an original architectural painted finish. Given the size of the project, the conservation department contracted additional help to complete the conservation and restoration of the library walls. Once the project started, the extreme sensitivity of the distemper painted finish to water and polar solvents posed significant challenges in the selection of treatment materials and methods. The application of any sort of mold making material to the friable and readily stained painted surface was impossible, meaning that a “touch-less” method was needed to re-create large missing raised plaster elements. A partnership with the 3-D scanning and printing program at Harford Community College provided some creative solutions for this project. Silicone solvents aided in removing some large spackle repairs from the walls by providing a safe way to remove a water-soluble material from a water-soluble surface. The material challenges of this project led to creative solutions that can hopefully be adapted for future use in architecture and other specialties.

Extending Arms of Christ is a 96’ L by 16’ H site-specific mosaic mural created in 1963 by Bruce Hayes for the front façade of Houston Methodist Hospital. Originally consisting of 3 large scale panels of Italian glass tesserae on a concrete bedding, the mosaic was designed to be the most prominent decorative feature above the entry doors to a major teaching hospital associated with Houston’s Baylor University medical school. Distinctly modern in character, the mosaic features the Christ figure with extended arms at the center of a geometric abstract background that is punctuated with stylized imagery of modern medical equipment, doctors, and historical figures, like Florence Nightingale. In 2014, RLA was contacted by Hunt Construction Group, a firm overseeing expansion of the hospital, to determine if the mosaic could be relocated into a 50’ atrium within the lobby of a new tower addition. Over the years, the mosaic had become obscured from the street by trees lining the sidewalk. A porte cochere, added in 1987, had covered up the bottom 4’ of the mosaic. Relocating the mosaic would allow it to be showcased once again for hospital patrons, as well as preserved and protected in a controlled interior setting. Moving an artwork of this size is challenging under any condition. This one was further complicated by its location over the hospital’s main entrance and next to the emergency room driveway, which barred the use of a crane or blocking of the street. A test probe revealed that the mosaic was separate from the wall of the building and therefore theoretically detachable. However, preclusion of the crane meant that the original panels, which measured 38’ 6” wide by 16’ high and weighed approximately 10,850 pounds, would need to be cut to allow them to be lowered by a gantry that could accommodate a maximum of 400 - 500 pounds. Our first task was to figure out how to do this without impacting the design elements, and determining in advance that the mosaic could later be re-assembled seamlessly. Because design of the new addition was completed by the time the mosaic relocation was considered, our next challenge was how to reinstall the artwork onto a metal stud wall. The engineer’s design solution involved the use of plywood, which raised concern because of possible warpage in the event of a catastrophic weather event. Said event occurred on August 25, 2017, when Hurricane Harvey devastated the Houston Metropolitan area. Installation of the 93 cut mosaic panels was completed at that point. Only the repair of the join lines remained to be done. As of this writing, we have not been able to return to Houston after Harvey. However, Hunt construction informs us that the mosaic is intact. As part of this presentation we will reveal what, if any, impact the hurricane had on the mosaic. The goal is to complete the conservation by December 2017.

The transportation and installation of the fresco mural Haitian Massacre, 1937, followed by its conservation, was not only challenging for the conservators but also for the engineers contracted for the project. The mural, created in 1974 by Dominican artists José Ramírez Conde and Roberto Flores, presented extensive damage from being hastily cut away from its original location and enduring three years of harsh environmental conditions after being left outdoors just covered by a tarp. Funded by the Ambassadors’ Fund for Cultural Preservation program, the project was lead by Dominican paintings conservator Hilda Abreu Utermohlen and U.S.-Argentinian Viviana Dominguez, mural conservator. The conservators took on the task of not only conserving the extensively damaged fresco, but also of advising on its preventive care, especially during its transportation from this exposed location to the Memorial Museum of the Dominican Resistance in Santo Domingo, Dominican Republic, and subsequent installation in the museum, where it could be appreciated by the public. 
Throughout the project, the authors faced technical and logistical challenges, due to the large size and heavy weight of the fresco wall, its poor condition, the long travel route from its location to the museum, the narrow entrance to the museum, its maneuvering for affixing it to the installation base, limitations in the availability of trained professionals in mural conservation and supplies, as well as budget constrains. These challenges were ingeniously sorted out thanks to the efforts and teamwork of the conservators and engineers, resulting in the successful completion of the project. Utermohlen and Dominguez presented the examination, planning and preparation phases of the project during AIC 44th Annual Meeting in Montreal in 2015, as a work in progress. On this presentation the authors will describe the completion of the project, consisting of its transportation, installation, and conservation treatment, followed by the repair of building features and exhibit completion by the museum. Highlights include: the frame used for securing the large wall during the 14 km ride through the city and into the narrow streets of the Colonial City, and the methods used for bringing in the severely damaged wall and securing it in place. Also, they will detail the conservation treatment activities performed, including consolidation and loss compensation with local materials and techniques similar to those used by the artists. In the conclusion, they discuss and reflect on the results and benefits derived from this project, not only for the specific preservation of this artwork, but also as a tool to convey its multiple values. Moreover, the international nature of the assembled team provided not only an opportunity to collaborate hand in hand in the exchange of knowledge, but also to build bridges of understanding among the participants. 

Traditional conservation techniques first uncovered the existence of Spanish colonial era frescoes on the interior walls of the Sacristy, in the Alamo Church, eighteen years ago. The stencil designs discovered encompass the entire room; at wainscot level, frieze band above entry doors, and along the arches of walls. The universal conservation lab techniques and analysis provided some of the answers however, there is still much to learn about the wall art in the Sacristy. Recently, conservation work in the Sacristy began and more evident questions arose; one inquiry: Is there another way of analyzing the pigment without removal? The answer is to this question is yes, by utilizing traditional analysis and state of the art technology. Through the use of a portable X-ray fluorescence spectroscopy (pXRF), the pigments that remained on the walls in the Sacristy were sampled and characteristic elements were identified. The 2000 paint analysis report identified four Spanish colonial tinted limewashes. The recent utilization of the pXRF analysis report, identified three unknown Spanish colonial tinted limewashes and metal leaf with high levels of copper. In addition to the pXRF, a scanning electron microscope, SEM with EDS capabilities was also used on selected sampled fragments. Elemental maps confirm the identification of vermillion (HgS). This advanced technology helps guide conservation efforts and leaves the microscopic historic elements intact. A second inquiry transpired: How do we visually see the invisible design elements? By employing multi-spectral imaging with ultraviolet florescence technical photography, 3-D photographic techniques: Reflectance Transformational Imaging (RTI) and DSLR photogrammetry were also a part of this project. The multi-spectral imaging documented invisible design elements, important application techniques; “pouncing”, “outlining”, and “block filling”. The multi-spectral imaging created high-resolution images along with 3-D models and photo mosaics. A third inquiry loomed: Why the sophisticated equipment used did not determine the shapes of areas where high levels of Lead (Pb) exist at the “tips” of an invisible floral design? The floral designs are located symmetrically on the original walls. The invisible floral designs contain an urn painted with ochre, reds and copper green. The shape of the urn is unknown. The project utilizing multi-spectral imaging and portable X-ray fluorescence spectroscopy results were exciting, but some of the unknown Spanish colonial designs remain a mystery. Is there a technology that can solve the mysteries in the Sacristy at the Alamo?

One hundred miles northeast of Santa Fe is Fort Union National Monument, the largest adobe ruin in North America and once the largest U.S. military reservation in the Southwest. Established as a National Monument in 1954, Fort Union challenged every succeeding generation of cultural resource specialists—archaeologists, architects, historians, engineers, scientists, conservators, and masons—to find a sustainable solution to the preservation of its earthen walls. The ruins of Fort Union now face unprecedented challenges as increased cycles of extreme weather undermine and topple walls. This research establishes a framework for the integrated study of the deterioration for earthen and masonry structures in the arid West. Risk and threat are examined as ‘vulnerabilities’ related to factors such as materials, construction, use, environment, weather, orientation, exposure, past treatment, and maintenance. The first phase of the project focused on preparing a database inventory and assessment of past records including historical photographs, construction documents, geotechnical and engineering analyses, administrative reports, and weather data (back to 1861) as well as past and current conservation and management strategies. The second phase examined individual vulnerabilities through a survey of one unit of the Fort—the Mechanics Corral in real and projected time. The field survey studied past and current conditions of the adobe walls to calculate wall loss, attrition, and profile changes over time. Real-time recording of the weather on site was conducted over one year, including monitoring of adobe walls using embedded temperature and moisture probes and time-lapse photography to test monitoring apparatus and record actual weather phenomena and wall responses to those phenomena. Finally, parametric software was employed to dynamically model current and future weather and potential climate-based threats to the site to design smarter responses to threats in the form of preventive conservation measures.

The Thomas Jefferson Memorial is an iconic monument that is widely identifiable both throughout the United States and the world. Located within National Mall and Memorial Parks, a unit of the National Park Service in Washington, DC, the design of this white marble monument combines classical iconography with modern construction to enshrine the ideals associated with one of this country’s founding fathers. Over the last decade, Memorial has become rapidly soiled by biofilm. The blackening effect of biofilm, a colony of microscopic organisms that adheres to stone surfaces, was first noticeable in discrete areas of the memorial’s white marble in 2006, and has become more pronounced in recent years. While it manifests itself in various ways, the biofilm is most pervasive—and most visible—on the Memorial’s dome. A multi-disciplinary team of conservators, architects and other professionals has been studying the growth on the Jefferson Memorial since 2014 to determine the best treatment options. After careful review, it was decided that the initial cleaning test would be performed using laser ablation. Laser ablation offers maximum protection to this significant cultural resource as well as the surrounding natural resources: by fine-tuning the laser settings to the specific stone and soiling types, laser operators can remove the biofilm without damaging historically sensitive marble. The use of laser is also an environmentally sound procedure and eliminates the need to use more aggressive chemicals or abrasive cleaning methods. Rigorous safety controls are maintained for the duration of the cleaning process to protect the public and the operators. The project will achieve the cleaning of a test area of 1,000 square feet on the northeast side of the Memorial. This presentation will evaluate the efficacy of laser cleaning to remove biofilm through the lens of this trial cleaning effort. This will include a discussion of: the decision process by which this cleaning method was arrived upon; the characterization and understanding of this biofilm phenomenon to date; the intricacies of implementing and scaling a cleaning project at this site; and what might be done to prevent or deter soiling recurrence in the future. A brief comparison of this phenomenon to the incidence of biofilm at other major sites in Washington, DC will also be included.

Biofilms are microbial communities, held together and to a substrate by a gel-like material. Biofilms cover all marble monuments. The biofilms that are considered visually unattractive are black; the black color is melanin, a pigment produced in response to UV radiation. Conservators are often tasked with “cleaning,” or “removing” a melanin-producing biofilm. To better understand these biofilms and concerns for their removal, the National Park Service’s Historic Architecture, Conservation, and Engineering Center executed a series of cleaning tests for long-term monitoring (15 years ago and 3 years ago); collaborated with the Center for Biofilm Engineering, Montana State University, and the Mathematics Department, Temple University on a National Science Foundation grant; and collaborated with students in the Biotechnology Lab, Thomas Jefferson High School for Science and Technology, Arlington, VA. Results from research and tests thus far conclude: 1. Biofilms are far more complex than one can imagine. 2. The bio-receptive surface of eroded marble is the perfect substrate for biofilms. 3. Stressing biofilms (many cleaning treatments) will produce immunities and a biofilm more resistant to that stress when it returns. 4. All brands of products containing quartenary ammonium compounds (quats) used for cleaning tests behaved the same. 5. Quats can be used as a diagnostic tool to determine the presence of biofilms, whether they contain melanin or not. 6. There is a relationship between biofilms, moisture, and salt deliquescence on a marble surface. Biofilms might be keeping surface salts in solution. 7. Microorganisms categorized as “extremeophiles” are found on white marble monuments in Washington, DC. 8. DNA sequencing of biofilm samples taken from a marble surface before and after cleaning tests is a way to understand success—or not—of cleaning. Collaborations continue, tests continue, observations continue, and research continues. Assumptions of biofilm activity and relationships to marble need to be constantly questioned. There is no solution to keeping eroded white marble monuments white, but with the efforts of many institutions, individuals, and industry, working together, we will learn more about biofilms and may even find a solution to keeping melanin-producing biofilms at bay.

This study focused on using petrographic analysis of brick located at the Josiah Benner Farm in Gettysburg, Pennsylvania to develop a more complete understanding of the architectural development of the Josiah Benner Farm and its involvement in the Battle of Gettysburg. Completed in 1862, the Benner Farm is significant for its involvement in the 1863 Battle of Gettysburg. The Benner Farmhouse provided cover for Union Soldiers and served as a field hospital while also being shot, shelled by artillery, and set afire. The Benner Family rebuilt the farmhouse soon after the battle and the farm remained in private ownership for the next 149 years before being acquired by Gettysburg National Military Park. Despite the farm’s proximity to one of the best documented battle sites in the United States, there is little archival information surrounding the farm. Traditional building practices in Southeastern Pennsylvania reused building materials where possible, further obscuring potential evidence related to the house’s involvement in the Battle of Gettysburg. As a result, traditional physical investigation was unable to shed light on the early years of the farm’s history. Petrographic analysis, primarily using microscopic evaluation and thin-section petrography, was performed on raw samples and polished thin-sections of historic masonry that were removed from both the farmhouse and the springhouse on the property. Emphasis focused on classifying manufacturing techniques, clay matrix, and source aggregate of each sample. This would presumably allow investigators to group similarly aged brick into unique clusters. Samples were taken across the structure and from interior locations whenever possible to avoid confusion from weathering forces. Additionally, several other samples from other regional structures were taken for comparison. Ultimately, six different groups of historic brick were identified, suggesting that the Benner Farm underwent significant rebuilding during its early history.

Bluestone, the common name given to a form of blue-colored feldspathic sandstone or greywacke quarried in Pennsylvania, New York, and Newfoundland, is now and was historically a popular building stone in the northeastern United States and eastern Canada. While generally durable, its laminar structure makes it susceptible to delamination, or the separation of layers of stone along their natural bedding planes. Examples of delaminating bluestone are easily found among historic buildings and monuments where the material was used. The nature of this form of deterioration has been well studied. However, a much less ubiquitous and less understood form of surface loss may also occur. In certain conditions, the stone may develop a hardened outer surface crust, as thick as 1 to 2 cm, which runs both parallel and perpendicular to bedding planes. This outer crust invariably detaches from the body of stone in a phenomenon known as case hardening or contour scaling. Contour scaling has been attributed to a variety of processes, such as precipitation of secondary minerals, hygroscopic swelling of constituent clays, thermal cycling, etc. This paper will discuss the use of microscopy in exploring the chemical and mineralogical alterations contributing to contour scaling in bluestone. This information may also be applied to understand scaling in other clay-bearing or laminated stone types. Applications for the presented research include diagnosis of stone deterioration in the field and development of effective conservation treatments. Examples will be drawn from New York City’s Highbridge Park and presented with photomicrographs of affected stones in thin-section.

Today, the historic concrete structures from the late 19th and early 20th century are facing severe degradation problems due to chloride ions, carbonation and other aggressive environmental factors. Although repair and reinforcement become urgent, effective methods are still under development. Electrochemical techniques (for example, realkalisation and electrochemical chloride extraction) and corrosion inhibitors have been used in protecting reinforced concrete buildings from corrosion. Recently, bidirectional electro-migrating (BIEM) is considered as a new technique, transferring corrosion inhibitors to the surface of steel rebar to prevent its corrosion. The materials acting as electro-migrating corrosion inhibitors are required to form cationic species in alkalinity concrete pore solution and with high mobility in concrete mortar. The available electro-migrating corrosion inhibitors now normally contain an amine, amino alcohol group or quaternary ammonium salt. But none of them can improve the durability of cement and concrete matrix directly. This study investigated the protective effectiveness of a new electro-migrating corrosion inhibitor--silicone quaternary ammonium salt (Octadecyldimethyl[3-(trimethoxysilyl)propyl] ammonium). Due to its molecular structure, it can create cations in solution and the silane group forms silicic acid by hydrolysis reaction generating silicon-oxygen bonds, which brings consolidating effect; besides the alkyl groups provide hydrophobicity. Experiments were performed in specimens that imitate reinforced concrete. The effectiveness of preventing corrosion was characterized by electrochemical measurements including potential dynamic polarization curve (PD) and electrochemical impedance spectroscopy (EIS) before and after BIEM treatment. The contents of nitrogen in different depth was measured to evaluate the efficiency of migration. Hydrophobicity was evaluated by contact angle after immersion of silicone quaternary ammonium salt. The results showed that the corrosion current (the corrosion kinetic parameters derived from the Tafel plots value) for steel in concrete before and after BIEM treatment was found to be reduced respectively. Improvement of the polarization resistance and charge-transfer resistance were determined by fitting parameters for specimens of EIS, suggesting that the resistance of concrete matrix and steel rebar were both increased after BIEM. The contents of nitrogen becoming higher as the depth increasing, means that silicone quaternary ammonium salt accumulated around the steel rebar. The contact angle was around 90 degree after immersion of silicone quaternary ammonium salt solution. The results obtained in the laboratory experiments indicate that BIEM treatment with silicone quaternary ammonium salt enhance the resistance ability to corrosion of steel rebar. In addition, this material has good migrating mobility in cement paste though BIEM and can maintain hydrophobicity. The investigated results reveal that BIEM technique with silicone quaternary ammonium salt could be a potential multifunctional treatment applied in conservation of historic reinforced concrete buildings.

Ancient stone artifacts and architecture deteriorate over time due to environmental factors, air pollution, salt efflorescence, and biodeterioration. As a result, effective stone consolidants are necessary for the conservation and protection of stone materials. Alkoxysilanes are effective stone consolidants, undergoing hydrolysis and condensation to produce a sol-gel coating capable of penetrating the stones porous structure. However, demands for improvements in commercial formulations have led to research efforts focused on increasing flexibility, “breathability” and durability without compromising water repellency and strength. In order to allow water vapor evaporation out of the pores after consolidation application, a “breathable” consolidant is required to permit the transport of water molecules. Polyhedral Oligomeric Silsesquioxane (POSS) structurally contains nano-meter sized pores, allowing for permeability of water molecules out of the stone in addition to added mechanical durability. Polydimethylsiloxane (PDMS) was utilized for increasing flexibility and water repellency. Currrent research is focused on formulating POSS, PDMS, and other additives into alkoxysilane stone consolidants for limestone and marble substrates.

From Wreckage to Relics: Conserving and Exhibiting Fragments from Frank Lloyd Wright’s Midway Gardens A financial failure from the beginning, Frank Lloyd Wright’s Midway Gardens was bulldozed and dumped into Lake Michigan just 15 years after its construction. Nearly a century later, three salvaged fragments from this entertainment center were uncrated at the Museum of Modern Art in New York, where they now form part of the Frank Lloyd Wright Archive, acquired jointly with Columbia University’s Avery Library. Built in 1914, Midway Gardens was a precursor to Wright’s textile block houses: employing cast stone blocks with complex geometric relief, it embodied a new use for concrete that united ornament and structure. However, by 1916, Midway Gardens had filed for bankruptcy, and many of the innovative design elements employed by Wright were altered by subsequent owners, including Edelweiss Brewing Company and E. C. Dietrich Midway Automobile Tire and Supply Company, to meet the needs of the various industrial aesthetics. These fragments – relocated first to Wisconsin, and now to New York – arrived with structural damages and without prior documentation. In preparation for MoMA’s major 2017 Wright retrospective, the museum’s Conservation Department partnered with Columbia University’s Historic Preservation Program to research and treat the works. Through examination, mock-ups, petrographic and chemical analysis, and research in the newly accessible Archive, the team shed new light on these works’ technology and history. The transfer of these fragments from the built environment – where they formed part of an evolving structure – to the museum collection – where they have become ossified relics – has shifted the way in which they are approached, both in interpretation and in preservation strategies. Their new home in acclimatized museum spaces expanded treatment options to include more reversible repair and loss-compensation materials than those typically used in historic preservation. This paper will cover the results of this year-long project that culminated in the treatment of these fragments, including the development of a technique to create large, vertical fills in cast stone with toned, Paraloid acrylic resin films and sand.

The Grand Egyptian Museum-Conservation Center (GEM-CC) will host the conservation and reconstruction of the Nilometer’s blocks. The research follows a values-based methodology where the archaeological, historic, artistic values and significance of the blocks guide the conservation and the reconstruction decisions. An impressive number of blocks—about 246—might belong to several tomb-chapels from the Late-Period. Other blocks have been excluded from the present study, since they date to other periods, and their provenance are likely different than the majority of the blocks. Since their discovery in the 1930s, the current location and most of the contents of the blocks reused in the substructure of the Nilometer at Roda Island have become obscured for the Egyptologists. After thorough research, it is quite certain that they came from the Nilometer at Roda Island. They had been reused in the substructure of the Nilometer and discovered during the restoration work, which took place from December 1934 till July 1939 by the Ministry of Public Works under the supervision of Kamel Osman Ghaleb Bey. 
The importance of the research is the primary study that confirms the blocks are from six tomb-chapels that date back to the Twenty Six Dynasty. The blocks still have the remains of pigments; blocks have a depiction of texts and vignettes from parts of the book of the dead. This depiction is considered one of the rare depictions from ancient Egypt, not present in other tombs, particularly late period tombs. It will be considered a research guide for those studying this time of ancient Egypt civilization. Complete documentation of the blocks starting from photographic documentation to digital drawings were made,  recording all details and information to make a new register. Digital drawings made to complete the missing parts of the stone depend on completing the depictions. 
The second part focus on investigation and analysis of the blocks which will make to identify the composition of the stone and the pigments to identify the source of the stone and type of color used at this time. The analysis will depend on the X-Ray diffraction (XRD) and portable X-ray fluorescence (pXRF) to trace elements to determine the elemental composition of the stone. Also Scanning Electron Microscope (SEM) is able to distinguish the texture of the stones. The reconstruction of the depictions depend on studies to reconstruct the scenes and texts, using the book of the dead as a reference, which includes the complete scenes. Through this, using facsimiles and translation of the texts of the complete scenes in comparison with the location of similar texts and vignettes in royal and private tombs, the original position of the blocks could be to a great extent reconstructed, which will allow for a proper and comprehensive museological display of the blocks in their original context, going as far as the complete reconstruction of parts of the tomb-chapels.